CHAPTER XII 



CYTOLYSIS AND DISINFECTION 



The first action of many toxic substances on cells is the de- 

 struction of the plasma membrane. The cell is then no longer 

 influenced by the osmotic pressure of the medium but may swell 

 or shrink as any other colloid mass, depending on certain condi- 

 tions. Animal cells after destruction of the plasma membrane 

 usually swell and disintegrate, a process known as cytolysis, 

 meaning the dissolution of the cell. It seems probable that death 

 of all cells is accompanied by cytolysis, but that other processes 

 sometimes mask the cytolytic changes. Thus, in the histological 

 fixation of cells the protoplasm is transformed into a stable mass 

 immediately after the destruction of the plasma membrane, so 

 that no swelling or shrinking follows the increase in permeability. 

 Since cytolysis means death of the cell, all cytolytics may be 

 used as antiseptics, destroying at least the active forms of micro- 

 organisms. 



The indifferent anesthetics, when their concentration exceeds 

 that necessary for the inhibition of cell activities, increase the 

 permeability of the plasma membrane. This increase, if slight 

 and momentary, may be reversible, at least in some cases. If 

 the semipermeability of the cell is entirely removed, cytolysis 

 and death occur. For this reason anesthetics have an antiseptic 

 action. Some active cells are more resistant to anesthetics than 

 others, the spores of bacteria usually not being killed, but merely 

 prevented from germinating so long as the anesthetic is present. 



The fact that anesthetics increase the permeability of cells 

 is illustrated by the fact that they accelerate autolysis. If tissue 

 is cut off from the blood supply, either by ligature of the vessels 

 or by removal from the body, and kept free from germs, it 

 digests itself, a process known as autolysis. Certain substances 

 accelerate autolysis. Chiari (1909) observed that ether accel- 

 erates autolysis. Hans Meyer (1909) explained its action as 

 an increase in permeability of the tissue, allowing the contact 



